Typically, a spinning fishing reel includes a spool non-rotatably mounted to a first end of a spindle extending outwardly from a front end of the reel housing and an oscillation mechanism located in the reel housing and connected to a second end of the spindle. A rotor of a spinning assembly is rotatably mounted to the reel housing and is configured for rotation about the spool. In use, by rotating a crank handle of the fishing reel, a user simultaneously causes the spool to move fore and aft along the longitudinal axis of the spindle and the rotor of the spinning assembly to rotate about the spool such that fishing line is wound about the spool's hub.
Typically, oscillation mechanisms include an oscillation gear 1 and a slider 2 fixed to a spindle 3 of the fishing reel, as shown in FIG. 1. A pin 4 on the oscillation gear engages a slot 5 on the slider, such that rotation of the oscillation gear about its center axis causes the slider, and consequently the spindle and attached spool, to move fore and aft along the longitudinal axis of the spindle. Frequently, a straight slot 5 is provided in the slider, the slot being arranged so that it is perpendicular to the spindle. This configuration results in a velocity profile for the slider and attached spool that is sinusoidal. The velocity of the spool along the longitudinal axis of the spindle is greatest when the pin engages the upper and lower end portions of the slot and is lowest when the pin engages the middle portion of the slot (as shown in FIG. 1).
As the user rotates the crank handle of the fishing reel at a constant angular velocity, the rotor of the spinning assembly also rotates at a constant velocity about the spool. As such, fishing line is wound onto the spool by the rotor at a constant rate. However, as noted, the velocity of the spool varies continuously as it moves fore and aft along the longitudinal axis of the spindle. As a result, more fishing line accumulates on the portions of the spool that are adjacent the rotor during the low velocity motion of the spool as opposed to those portions adjacent the rotor during high velocity motion of the spool. As such, excess fishing line tends to accumulate at the extreme fore and aft portions of the hub while the central portion of the hub tends to accumulate less fishing line than is desired. Uneven winding of fishing line about the spool can result in the spool having a reduced capacity for storing fishing line, tangling of the fishing line during casting, and reduced accuracy during casting, as well as other issues.